Those words echo concerns by other centrist Democrats about the overall cost of healthcare reform. Senate Budget Committee Chairman Kent Conrad (D-N.D.) said Sunday that a health bill would have to cost "significantly less" than is currently estimated in order to win enough votes to make it out of Congress.

Markey, a freshman lawmaker from a relatively conservative Colorado district, argued that the centerpiece of the bill, a public (or "government-run") option for consumers, would actually cost very little, but should only be funded through premiums in the plan, and not government subsidization.

She also pledged to only support a bill that addresses long-term budgetary concerns.

"I won't vote for a bill that doesn't bring efficiencies into the system and lower the cost," she told attendees of the town hall.